The use of flexible connector joints between a feed hopper and a reactor housing so that the feed hopper may be weighed separately from the reactor is well known, as evidenced by U.S. Pat. Nos. 4,331,084 (Fitch et al.), 4,528,848, which issued on May 25, 1982, (Hafner), which issued on Jul. 16, 1985, and 4,767,258 (Solvi et al.), which issued on Aug. 30, 1988.
U.S. Pat. No. 4,331,084 discloses a lower feed chute portion coupled to a weigh bin by means of a flexible, airtight seal so as not to support the weigh bin but only to guide the fuel into the inlet of the combustion chamber while simultaneously preventing ambient air from entering the combustion chamber.
U.S. Pat. No. 4,528,848 discloses a pneumatic conveying system comprising sealing elements, preferably semi-elastic or elastic seals, provided between the rotor and the housing. Materials which may be used as semi-elastic seals, are seals of tetrafluoroethylene or, respectively, polyurethane seals having approximately 90.degree. shore hardness. Softer synthetic materials, such as rubber, natural caoutchouc, vinyl caoutchouc or felt gaskets may also be used as elastic seals.
U.S. Pat. No. 4,767,258 discloses a storage chamber, feed hopper and furnace separated from each other by means of compensators in such a manner that the chamber and hopper may be weighed separately by means of pressure cells.
The aforementioned patents disclose various flexible connectors disposed between hoppers and reactors. However, these flexible connectors have been found to be inadequate for weighing and delivering soda ash in a plasticizer process. Plasticizer reactors have a design rating of 1.724.times.10.sup.5 N/m.sup.2 at 195.degree. C. (i.e., 25 psig/FV at 352.degree. F.). The normal maximum working temperature is 183.degree. C. (330.degree. F.). The materials handled by plasticizer reactors and hoppers necessitate a flexible connector which is resistant to solvent, acids and other chemicals. Conventional connectors called upon to contain pressure and/or vacuum typically have a rigidity which introduces an error in the weighing of the material in the hopper. This is especially true if either the receiver or the weigh hopper move with respect to one another (i.e., sudden thermal growth, wind effects, sudden charging of one vessel, etc.).
The present inventors have designed a flexible connector assembly which is rated to withstand increased pressure and vacuum, and which is also temperature and acid/solvent resistant. The device according to the present invention comprises a flexible fabric resistant to temperature and acid/solvent fumes held in a perforated stainless steel, telescopic assembly. The fabric is fastened at each end flange, and is restrained outwardly by telescoping sleeves or shrouds and inwardly by a perforated metal inner sleeve or shroud. A Teflon.RTM. tube or chute is held inside the assembly to prevent soda ash from building up on the perforations or fabric. This "sock" design has successfully proven that 204.12 to 272.16 kg (i.e., 450 to 600 lb.) charges can be conveyed and charged into the reactor and be proven within 0.91 kg (i.e., 2 lbs.) of the target weight.
The present invention also provides many additional advantages which shall become apparent as described below.